Method of manufacturing a zeolitic adsorbent useful for aromatic separation

Abstract

Abstract A method of manufacturing a solid adsorbent which method comprises the steps of: contacting a base material containing type X or type Y zeolite with a fluoride-containing solution of sodium hydroxide at first ion exchange conditions to effect the addition of sodium cations to and the extraction of alumina from the base material; ion exchanging the base material at second ion exchange conditions to effect the essentially complete exchange of sodium cations; and, drying the exchanged zeolite at conditions ro reduce the LOI at 900*C. to less than about 10 wt. %. The sodium cations can be essentially completely exchanged with either barium and potassium cations in a weight ratio of from about 1.5 to 200 or with barium cations alone. The combination fluoride-caustic treatment prior to the exchange with potassium and barium or with barium alone produces a superior adsorbent for separating the para isomer from a feed mixture comprising at least two bi-alkyl substituted monocyclic aromatic isomers, including the para isomer, the isomers having from 8 to about 18 carbon atoms per molecule. The adsorbent so produced has faster para isomer transfer rates and higher aromatic capacity than one produced either from untreated base material or from base material treated with fluoride or caustic alone. Additionally a fluoride treatment of base material alone or in combination with or subsequent to a caustic treatment, prior to potassium and barium or barium ion exchange, essentially eliminates a troublesome dustiness characteristic of adsorbents prepared from untreated base material.

Inventors

• 👤 Donald H Rosback

Bibliographic Details